This invention relates to an apparatus and method which use a fluid heated roll. The invention is particularly applicable to fiber processing equipment such as fluid (i.e. steam) heated draw rolls. Such draw rolls are rotated at relative velocities so as to stretch fibers to thereby decrease their diameters. Heating such draw rolls particularly enhances the properties of the processed fibers and assists in preventing the fibers from breaking while being stretched over such draw rolls. The final processed fiber products are used to make yarns.
One difficult problem encountered in the art of fiber processing has been the early and accurate detection of a "cold", steam-heated roll (i.e. a draw roll whose steam supply is decreased or interrupted entirely). It is important to quickly detect such a cold roll so that the processing equipment can be shut down to minimize the production of resulting bad product.
One prior technique for detecting a cold roll involves detecting the temperature of the steam supply to the roll. Such a technique can give a false indication of a hot draw roll when steam is leaking from the apparatus downstream from the temperature detection location in the steam supply line but upstream from the draw roll.
Another prior technique for detecting a cold draw roll involves directly detecting the temperature of the draw roll exterior surface by contacting a hand-held pyrometer with the draw roll surface. This technique can give highly inaccurate temperature readings due to factors such as friction between the draw roll surface and pyrometer. Furthermore, if for any reason the norma) flow of steam to the draw roll is decreased or cut off entirely, the technique does not detect such a condition until the surface of the draw roll has actually cooled down. By that time, bad product will have already been produced.